Control for blowers



Dec. 22, 1931. c, R. wA|, l-:Rl 1,837,382

CONTROL FOR BLowERs Filed May 13, 1929 2 SheetsfSheet l N 11K@ w i 11:'6"WH x n o -o Q D w N I -n Q w N w $7' N lo ,7 i

u gl) lo Y Q1 Patented Dec. 22, 1931 Y N UNITED lSTATES 'PATENT vOFFICE@ cani. n. WAELEE, 0E 'rn/Enron, NEwuEEsEY, Assieivonjro DELaval., STEAM TUE- BINE COMPANY, or TRENTON, NEW JERSEY, A oonronarroivor NEW JERSEY CONTROL FOR BIlZlO'YTllilRS i `Application ledJlIay 13,1325.). SerialV No. 362,548.`

This invention relates to /controllingmeans for blowers particularlyadapted to secure proper operation of blast furnace blowers.

In the manufacture of pig iron, it is' highly essential that duringyblast periods the blowing engine delivers to theY furnace a constantamount of air since the proportion of oxygen must be kept very close toa fixed amount relative to the ore and lime-in' the fur-l nace.Accordingly, blast furnace blowers have been equipped with governorsadapted to maintain a constant volume ofV air independently ofvariations in pressures existing at the furnace. Such governingarrangement is made adjustable that the operator may predetermine theconstant volume to be delivered in accordance with the demand of thefurnace.

After a furnace has been running for a certain number of hours the metalmust be drawn. During the drawing period .the pressure must be veryYconsiderably reduced, inasmuch as the rate of discharge is dependentthereon. It is the practice in some places, for example, to maintainone-half the blast furnace pressure during the casting period afterwhich the pressure is again reduced, the pressure being heldsubstantially constant during each of the latterperiod's.

Heretofore these lower, substantially constant pressures have beenobtained by reduc# Y ing the speed of the blower and manually operatinga large bleeding valve, called a snorting valve, near the entrance ofthe V'compressed air into the furnace. This procedure has been foundquite unsatisfactory by reason of the difficulty in maintaining thepressure sulficiently constant, as is necessary since slight variationsin pressure produce large differences in therate of discharge, which, ifincreased to any degree, makes the handling of the metal impossible witha given amount of labor and equipment.

Accordingly, it is the broad object of the present invention to provideimproved means Y for controlling ablower whereby either constant volumeor constant pressure may be maintained. VDetailed objects, as willappear hereafter, relate to the provision of simple interconnections forthe controls whereby a-l simplified and readily operated blowermechanism'is provided.

In the drawings: Y "Fig 1 is adia'grammatic view showing the variousconnections of the control system;

Fig. 2 is a vertical Vsection through th main controlling valve; and i lFigs. 3 and l arer fragmentary views of details. l 1

In the present vembodiment of the invention, the controlling means areparticularly adapted to provide for the delivery of air at eitherconstant pressure or constant volume from a rotary blowerdriven by asteam turbine of any desirable type. As disclosed, the turbine isprovided with a steam chest 2 in which are locateda number of valves 4lserving to control the fiow of steam from the steam chest to varioussets of nozzles in the ordinary manner, control of speed being eicientlyregulated by the successive opening and closing of various valves tosecure the admission of steam to definite sets of nozzles. Y The suc`cessive opening and closing of the valves 4 is accomplished through themedium of levers 6 operated upon by cams 8 carried by a cam shaft 10 toopen the valves against the pressures of springs which normally tend tohold them closed. Cam shaft 10is rotated in oppositedirections'through'the medium of oil pressure operating on opposed wingsof aV rotary piston 12, the oil` being admitted toV one wing or theother through conduits 14 and 16. Rotation of the piston and cam shaftin the direction indicatedby an arrow in Fig. 1 will result in thesuccessive opening of the valves 'from left to right.

The rotary blower driven by the turbine is'indicated by numeral 17. Thecontrol of flow of oil under pressure through conduits 14 and 16 iseffected through a valve such as shown in Fig. 2. Conduit 14 opens intoan annular port 18. while conduit 16 opens into an annular portQOarranged vwithin a cylinder'inwhich is mounted for vertical sliding-movementra f sleeve 22 having openings normally arranged to align withports 18and 20 and alsofhav-` ing an opening betweenthe said two`openings arranged to align with the central port 24, with whichcommunicates a line 26 through which oil is supplied under pressure.Slidable within sleeve 22 is a pilot valve consisting of two pistons 28and 30 carried by a piston rod 32, the upper end of which is connectedto a lever 34 carried by a shaft 36,

A collar 38 is secured on the upper end of sleeve 22 and is acted uponby a spring 40 which normally tends to raise the sleeve. This tendencyis counterbalanced by the pressure of a lever 42 bearing on the upperend of the sleeve, which lever is pivoted at 44 to the valve casing andis, at its free end, normally urged downwardly by a spring 48 whichisofv suiiicient strength toA overcome the tendency of spring 40 toraise the sleeve. The free end of the lever is` also connected by aflexible or rigid connection 46 to one end ofthe lever 5.0 pivoted-onthe steam.

chest, the opposite end of which carries a cam following roller actedupon by a cam 52. mounted -on shaft 16.

In the operation of the mechanism, a. rise ofgstem 32 will carry thepilotvalves28 and 3.0. upwardly out of their normal closing alignmentwith the openings in sleeve 22. Asa result, oil under pressure may flowthrough line26 and the central ports of the sleeve upwardly within thesleeve and through port 18 into conduit 14, thus causing a motion of camshaft l() in the direction ofthe arrow in Fig. l. This movement willefectthe successive opening of the throttl valves with the resultantincrease, of .speed of` the. turbine. At the same time, cam 52 will actupon lever 50, raising lever 42 and thus permittingf an` upward movementof sleeve 22 under the action of spring 40. The openings in sleeve4 22will then be again brought into, aclosing relationship with pilot valves28.and 30 so that the flow of oil is cut off andthe rotation of shaft l0limited.

The, above action of the control valve is-of the. ordinarytype. andresults in an increase of speed of the turbine without an objectionable`floating characteristic. An4 opposite movement of stem 32 will effect inan analogous fashion the closure ofthe throttle valves and a decrease inthe speed of operation ofthe turbine.

Sleeve 22 also carries a collar 54 with which a.,pist0n 56=is arrangedto abut ifmoved upwardly. Piston 56V is normally held downwardly, withinthe casing by means ofV a spring; 58. Bythe connections as described,sleeve22 is freeto move upwardly independently. of thepistou, whileupward movement ofthe piston will carrythe sleeve upwardly.

" reconduit 62 entersthe cylinder in which piston 56 slides beneath thevsame, while aA small*aperture 60 'is provided through the piston. topermitthe normalI passageA of oil therethrough as longA asl the, Oil;enters the; 5 cylindenat a comparatively low velocity. It`

will be understood that all of the overflow oil from the valve andconnections is arranged to flow back into a suitable sump from which itis repumped under pressure to the lubricating system and controllingdevices of the mechanism.

A pumpl 64 which may be of the ordinary tooth gear construction isdriven from the turbine shaft 65 and supplies oil under relatively highpressure through conduit 26. A relief valve 66 communicates with theconduit and permits an overflow, if the normal pressure is exceeded,into a pipe 68 and thence to the bearings of the machine, or other partsto be lubricated. A relief valve 69 set for lower pressure than reliefvalve 66 prevents the attainment of extremely high pressure in the oilline.

' The oil line 68 communicates with the upper side of a diaphragmsecured to a steam controlling valve 70, forcing the diaphragminopposition to a spring in a direction to close off the fiow 0f steamthrough the valve 70. If, for any reason, the pressure of the oil fallsso that oil is not delivered through relief valve 66, or is onlydelivered in insuflcient quantity, the pressure above the diaphragm willbeinsuflicient to maintain the steam valve closed againstl the pressureof the spring. Accordingly, this valve will open f and admit steam to aturbine 72 connected with a centrifugal pump 74 which rwill lift oillfrom the sump and discharge the same through a discharge line connectedto line 26, in which discharge line is located a. check l valve 76permitting passagel from` the centrifugal pump.

The devices above described are particularly useful 'in this deviceinasmuch as a considerable variation of speed of the turbine will occur.At low speeds, the pump 64 will fail to deliver sufficient oil toproperly lubricate the machine and maintain the controliing devices inoperative condition. Consequently, it is necessary to bring theauxiliary pump 74 into action to maintain a suflicent pressure. When theturbine is brought up to its normal high speed, the auxiliary pump willbe cut Il l i) out of action and pump 64 will supply all of theoilnecessary for the system.

A second pump 78 deliversv oil through conduit 62 beneath piston 56. Atnormal speeds of operation of the turbinethe oil is delivered atrelatively small velocity so that it can pass freely through opening 60without causing piston 56 to rise. Onf the other hand, if the turbineacquires an excessive velocity the piston 56 will be` raised, carryingupwardly sleeve 22 and thus effecting either a closure ofrthe portsopenedby pilot valves 28 and 30er an opening. of the ports so astopermit oil under pressure to flow through conduit 1-6and thus effect arotation of thecam shaftto close the throttlevalves of; the turbine.

Secured toshaft 36 which, as stated above, carries lever 34 connected tothe pilot valves, is an arm 80, the hubof which -is provided with anabutment 82 arranged to engage, when moved downwardly as viewed in Fig.-4, an abutment 84 carried by the hubot a liever 86 mounted for freerotative movement about shaft 36. The opposite side'o' the hub of arm isprovided with an abutment 94 which is arranged to engage an abutment 92for-med on a sleeve carried by a shaft 88 `when abutment"94 ismovedfupwardly as viewed inlig.'4. Shaft 88 'is mounted co-v aXiallywith, but independently of, shaft 36 and Carries at .its'outer end alever 96. It will be seen from this construction that arm 80 willpositively move arm 86 when it moves in one direction but willnot'aiiect the arm when it moves in an opposite direction, the reversebeing true of its action upon lever 96.

`Situatedabove arm 86 is a volume governor device'comprising a casing inwhich is secured a diaphragm r98. This diaphragm carries'a rod extendingdownwardly through the casing and connected to a lever 100 having aulcrum at its other end, as indicated in Fig. 1, and being connected atits free endA with lever ,86 byV a rod 102. A spring 104 is secured atits upper end to lever 100 and at its lower end to a horizontal arm of abell crank 106, the other arm of which is connected through a suitablelinkage with' an adjustino' lever 108 mounted on a control panel.ovement of lever 108 will result in an adjustment of the tension ofspring '104 with a resultant change in operation of the control, as willbe later described. Lever 108 is adapted to be maintained in an adjustedposition by any suitable means. i. The casing above and below thediaphragm 98 communicates respectively through conduits `110 and 112with the throat and entrance of a Venturi tube 114 arranged in theintake of the blower 17. Due to this arrangement, it will be seen thatan increase in volume of air flowing into the blower will produce anincrease in the difference in pressure on the opposite sides of thediaphragm. Due to the connections, it will be seen that this diierenceis substantially independent of the pressure existing at the intake, sothat the difference in pressure on the diaphragm is dependent primarilyon the volume of air flowing into the blower.

A similar diaphragm 115 is mounted in a casing above lever 96 and issimilarly connected with a lever 116, the free end of which is connectedas indicated at 118 with lever 96. A spring 120 secured at its upper endto lever 116 is connected at its lower end through suitable linkages toan adjustable lever 122, which may be maintained in an adjusted positionin any suitable manner so that a predetermined tension may be producedin spring 120. The

"upper and lower sides of diaphragm 115 communicate respectively throughva passage 124 and a conduit 126 with the` atmosphere and the compressedair inlet adjacent Vthe furnace.` It will thus be seen that movement ofthe diaphragm isy effected by a change in pressure at the furnace. -Y

A rod 128 is received within the bifurcated upper end oi arm 80 and isconnected to a lever 130 which may be secured in either of `two extremeadjusted positions by means of a suitable controlling lever mounted onthe control board. The free endv of rod 128 is provided with an abutment132 againstv which ia spring 134 bears, the inner end of the springabutting against a collar 136 slid.- ably mounted on rod 128. Anlabutment 138 limits movement of a second spring 140, the opposite endofwhich abuts a` collar 142 slidably mounted on the rod. Collars 136 and142 are Vlimited 'in their movements t0- ward each other by means ofsuitable pins or the like.' The bifurcated upperend of arm 80 isprovided with a suitable head 144 arranged to selectively abut collars136'or 142 accordingly as arm 130 is moved to either of its adjustedpositions, this movement effecting a compression of one of the springsto correspondingly move arm 80 so that its hub contacts -with abutment84 or 92. f

In considering the operation of the devicelet it be assumed, the machinebeing at rest, that lever 130 is set as shown in Fig. 1,

whereby arm 80 will be moved in a clockwiseV direction into engagementwith arm 86 which will be in its eXtreme lower position due to thetension on spring 104 and the absence of differences in pressure on .thesides of diaphragm 98. Spring 134 will be slightly compressed therebymaintaining the engagement of abutments 82 and 84 in all positions ofadjustment.. Due to Vthe eX- treme movement of arm 80, pilot valves 28Vand 30 will be in their eXtreme upper positions, opening communicationbetweenline 26 andconduit 14. Y y r It, now, steam is turned on, oillpump 74 will operate, forcing oil into line 26 and thus effectingmovement of cam shattlO Vto open the steam valves to their full amount,the opening movement being limited by the upward movement of sleeve 22to shut off the flow of oil into conduit 14.' Y j As the turbine gainsspeed, difference in pressure occurs on the sides "of the diaphragm 98,resulting in an upward move-4 ment of lever 86vwhichk carries arm 80 inacounter-clockwise direction moving the pilot valves downwardlyandelecting successive closure .of thethrottle valves. EquilibriumV willbe' attainedwhen the dierential' pressure ondiaphragm98 is balanced byspring 104 V'and the valves are so set as to maintain a Vconstant volumeotair entering the blower.- Y It jwill be seen thatthis equilibrium'po-`sition is dependent onthe tension of spring 104, a. change in thetension of which, through manipulation olever 108, will resultin anattainment otf equilibrium ata di'erent constant volume. Any deviationin the volume entering the blower will result in a compensating changein speed of the turbine as will be obvious.

AS was stated above, in the operation of blast furnaces, the constantpressure maintained` during the castingis less than the pressure duringthe blasting. When the constant 4pressure operation is desired, lever130 is set so that spring 140 moves lever SO in a counter-clockwisedirection against abutment 92 of collar 90. This movement results in adownward movement of pilot valves 28 and 30 with resultant closure otthe throttle valves and slowing down of the machine. It will be seenthat now the tension of spring 120 determines the equilibrium speed andthat changes in pressure will be compensated by change in speed of theblower. rThe operator may, accordingly, determine the constant pressureof operation by suitable adjustments of lever 122.

For simplicity, levers 86 and 96 have been shown as connected directlyto diaphragme 98 and 115. For greater sensitivity, motion multiplyingdevices of the usual type applied to.v diaphragm controlling` mechanismsmay be used to obtain large motions of the levers for slight movementsof the diaphragms.

While the Venturi tube is shown as located in the intake of the bloweror compresser, it will be obvious that it may be located in thedischarge.

that I claim and desire to ters Patent is: Y

1. In combination witha compressor and dri-ving means therefor, meansJfor controlling the delivery of theicempressor, a device operating`responsively to the pressure of gas hanprotect by Letdled by thecompressor, a device operating responsively to the volume of gas handledby the compressor, and means for selectively rendering theicontrollingmeans subject to actuation by the operation ofeither the pressureresponsive device or the volume responsive deviceV to effect thedelivery of compressed gas at either substantially constant pressure orsubstantially constant volume.

EZ.` In combination with a compressor and driving means therefor, meansfor controlling` thespeed ot the drivin g means, a device operatingresponsivel-vT to the pressure of gas handled by the compressor, adevice operating responsively to the volume of gas handled bythe-compressor, and means for selectively rendering;4 the controllingmeans subject to actuation by the operation of either the pressureresponsive device or the volume responsive deviceftoef'ect the deliveryof compressed` gas at either` substantially constant pressure orlsubstantiallyl constant volume.

3. In combination with a compressor, and a driving turbine thereforhaving valve means for controlling the flow of propelling fluid thereto,liquid operated means for operating the valvemeans, a valve forregulating the delivery of liquid to said liquid operated means, meansfor supplying liquid under pressure to the valve, the operation of saidsupplying means beingI dependent on the speed of operation of thecompressor, auxiliary means forv supplying liquid` under pressure tothevalve when insulficient pressure is produced bythe first named supplyingmeans, a device operating responsively to the pressure of gas handled bythe compressor, a deviceoperatingresponsively to the volume of gashandled by the compressor, and means for selectively rendering saidvalve subject to ac tuation by the operation of either the pressureresponsive device or the volume responsive device to eiect deliveryof'compressed Lgasat either substantially constant pressureor-substantially constant volume.

In testimony of which invention, I have hereunto set my hand, atTrenton, New Jersey, on this 9th day of May, 1929.

CARL R. WALLER.

